How to use an enhancement mode N-MOSFET as a variable resistor, where the increasing gate voltage increases the drain-to-source resistance - Quora
A depletion type N-channel MOSFET is biased in its linear region for use as a voltage controlled resistor. - Sarthaks eConnect | Largest Online Education Community
![How to build a voltage-controlled current sink / voltage-controlled resistor - Electrical Engineering Stack Exchange How to build a voltage-controlled current sink / voltage-controlled resistor - Electrical Engineering Stack Exchange](https://i.stack.imgur.com/7VLy2.png)